The 3HDM model parameter space is limited by measurements of \(B\)  meson rare decays and \(B\)  meson mixing. A particularly strong constraint is given by \(B \rightarrow X_s \gamma \) , which is altered from the SM prediction by the additional contributions of the loop diagram of the charged Higgs boson.
The Heavy Flavor Averaging Group (HFAG) gives the the experimental value for \({\rm BR}(B \rightarrow X_s \gamma )\)  as [1]}
\({\rm BR}(B \rightarrow X_s \gamma )_{\rm exp}=(3.32\pm 0.15)\times 10^{-4}\) 
